Fluid simulation in moving object
For liquids contained within a mesh you should always ensure that the ‘container’ has thickness (either by modelling the thickness or by adding a Solidify modifier. You should then ensure that the Resolution of the fluid domain is set high enough so that each cell in the simulation is smaller than the minimum thickness of the container. This will ensure that the fluid does not protrude outside the mesh. 

For an cleaner boundary (eg, if the container is transparent) between the fluid and its container (to stop them intersecting) you can add a Boolean modifier to the fluid to remove the parts that intersect into the container mesh.